Successful cafe owner Sung Soo (Son Hyun Ju) has a seemingly perfect life with his wife (Jeon Mi Sun, The Executioner), children and luxury apartment. But he suffers from mysophobia and harbors a dark secret concerning his estranged older brother. After hearing that his brother has gone missing, Sung Soo goes to check his brother's rundown apartment and sees strange codes scrawled everywhere. A scared woman who lives nearby, Joo Hee (Moon Jung Hee, Deranged), tells him that his brother is watching her daughter. Soon, Sung Soo notices that the same strange codes are appearing around his home. A dangerous game of Hide and Seek has begun.